Cargando…

The Autophagic and Endocytic Pathways Converge at the Nascent Autophagic Vacuoles

We used an improved cryosectioning technique in combination with immunogold cytochemistry and morphometric analysis to study the convergence of the autophagic and endocytic pathways in isolated rat hepatocytes. The endocytic pathway was traced by continuous uptake of gold tracer for various time per...

Descripción completa

Detalles Bibliográficos
Autores principales: Liou, Willisa, Geuze, Hans J., Geelen, Math. J.H., Slot, Jan W.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1997
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2132457/
https://www.ncbi.nlm.nih.gov/pubmed/9008703
_version_ 1782142451094388736
author Liou, Willisa
Geuze, Hans J.
Geelen, Math. J.H.
Slot, Jan W.
author_facet Liou, Willisa
Geuze, Hans J.
Geelen, Math. J.H.
Slot, Jan W.
author_sort Liou, Willisa
collection PubMed
description We used an improved cryosectioning technique in combination with immunogold cytochemistry and morphometric analysis to study the convergence of the autophagic and endocytic pathways in isolated rat hepatocytes. The endocytic pathway was traced by continuous uptake of gold tracer for various time periods, up to 45 min, while the cells were incubated in serum-free medium to induce autophagy. Endocytic structures involved in fusion with autophagic vacuoles (AV) were categorized into multivesicular endosomes (MVE) and vesicular endosomes (VE). Three types of AV—initial (AVi), intermediate (AVi/d), and degradative (AVd)—were defined by morphological criteria and immunogold labeling characteristics of marker enzymes. The entry of tracer into AV, manifested as either tracer-containing AV profiles (AV(+)) or fusion profiles (FP(+)) between AV and tracer-positive endosomal vesicles/vacuoles, was detected as early as 10 min after endocytosis. The number of AV(+) exhibited an exponential increase with time. FP(+) between MVE or VE and all three types of AV were observed. Among the 112 FP(+) scored, 36% involved VE. Of the AV types, AVi and AVi/d were found five to six times more likely to be involved in fusions than AVd. These fusion patterns did not significantly change during the period of endocytosis (15–45 min). We conclude that the autophagic and endocytic pathways converge in a multistage fashion starting within 10 min of endocytosis. The nascent AV is the most upstream and preferred fusion partner for endosomes.
format Text
id pubmed-2132457
institution National Center for Biotechnology Information
language English
publishDate 1997
publisher The Rockefeller University Press
record_format MEDLINE/PubMed
spelling pubmed-21324572008-05-01 The Autophagic and Endocytic Pathways Converge at the Nascent Autophagic Vacuoles Liou, Willisa Geuze, Hans J. Geelen, Math. J.H. Slot, Jan W. J Cell Biol Article We used an improved cryosectioning technique in combination with immunogold cytochemistry and morphometric analysis to study the convergence of the autophagic and endocytic pathways in isolated rat hepatocytes. The endocytic pathway was traced by continuous uptake of gold tracer for various time periods, up to 45 min, while the cells were incubated in serum-free medium to induce autophagy. Endocytic structures involved in fusion with autophagic vacuoles (AV) were categorized into multivesicular endosomes (MVE) and vesicular endosomes (VE). Three types of AV—initial (AVi), intermediate (AVi/d), and degradative (AVd)—were defined by morphological criteria and immunogold labeling characteristics of marker enzymes. The entry of tracer into AV, manifested as either tracer-containing AV profiles (AV(+)) or fusion profiles (FP(+)) between AV and tracer-positive endosomal vesicles/vacuoles, was detected as early as 10 min after endocytosis. The number of AV(+) exhibited an exponential increase with time. FP(+) between MVE or VE and all three types of AV were observed. Among the 112 FP(+) scored, 36% involved VE. Of the AV types, AVi and AVi/d were found five to six times more likely to be involved in fusions than AVd. These fusion patterns did not significantly change during the period of endocytosis (15–45 min). We conclude that the autophagic and endocytic pathways converge in a multistage fashion starting within 10 min of endocytosis. The nascent AV is the most upstream and preferred fusion partner for endosomes. The Rockefeller University Press 1997-01-13 /pmc/articles/PMC2132457/ /pubmed/9008703 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Article
Liou, Willisa
Geuze, Hans J.
Geelen, Math. J.H.
Slot, Jan W.
The Autophagic and Endocytic Pathways Converge at the Nascent Autophagic Vacuoles
title The Autophagic and Endocytic Pathways Converge at the Nascent Autophagic Vacuoles
title_full The Autophagic and Endocytic Pathways Converge at the Nascent Autophagic Vacuoles
title_fullStr The Autophagic and Endocytic Pathways Converge at the Nascent Autophagic Vacuoles
title_full_unstemmed The Autophagic and Endocytic Pathways Converge at the Nascent Autophagic Vacuoles
title_short The Autophagic and Endocytic Pathways Converge at the Nascent Autophagic Vacuoles
title_sort autophagic and endocytic pathways converge at the nascent autophagic vacuoles
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2132457/
https://www.ncbi.nlm.nih.gov/pubmed/9008703
work_keys_str_mv AT liouwillisa theautophagicandendocyticpathwaysconvergeatthenascentautophagicvacuoles
AT geuzehansj theautophagicandendocyticpathwaysconvergeatthenascentautophagicvacuoles
AT geelenmathjh theautophagicandendocyticpathwaysconvergeatthenascentautophagicvacuoles
AT slotjanw theautophagicandendocyticpathwaysconvergeatthenascentautophagicvacuoles
AT liouwillisa autophagicandendocyticpathwaysconvergeatthenascentautophagicvacuoles
AT geuzehansj autophagicandendocyticpathwaysconvergeatthenascentautophagicvacuoles
AT geelenmathjh autophagicandendocyticpathwaysconvergeatthenascentautophagicvacuoles
AT slotjanw autophagicandendocyticpathwaysconvergeatthenascentautophagicvacuoles